The impact of pre-admission morbidity level on 3-year mortality after intensive care: a Danish cohort study

Resuscitation and Preparation of the Emergency General Surgery Patient

Traditionally, the workflow surrounding a general surgery patient allows for a period of evaluation and optimization of underlying medical issues to allow for risk modification; however, in the emergency, this optimization period is largely condensed because of its time-dependent nature. Because the lack of optimization can lead to complications, the ability to rapidly resuscitate the patient, proceed to procedural intervention to control the situation, and manage common medical comorbidities is paramount. This article provides an overview on these subjects.

Healthcare utilisation trajectories in patients dying from chronic obstructive pulmonary disease, heart failure or cancer: a nationwide register-based cohort study

OBJECTIVES

To investigate illness trajectories as reflected by healthcare utilisation, including hospital and intensive care unit admissions, consultations in general practice and home care provision, before death comparing people dying from chronic obstructive pulmonary disease (COPD), heart failure and cancer.

DESIGN

Nationwide register-based cohort study.

SETTING

Data on all hospital admissions, including intensive care unit admissions, consultations in general practice and home care provision were obtained from nationwide Danish registries.

PARTICIPANTS

All adult decedents in Denmark dying from COPD, heart failure or cancer between 2006 and 2016.

OUTCOME MEASURES

For each day within 5 years before death, we computed a daily prevalence proportion (PP) of being admitted to hospital or consulting a general practitioner. For each day within 6 months before death, we computed PPs of being admitted to intensive care or receiving home care. The PPs were plotted and compared by regression analyses adjusting for age, gender, comorbidity level, marital/cohabitation status, municipality and income level.

RESULTS

Among 1 74 086 patients dying from COPD (n=22 648), heart failure (n=11 498) or cancer (n=139 940), the PPs of being admitted to hospital or consulting a general practitioner showed similar steady progression and steep increase in the last year of life for all patient populations. The PP of being admitted to intensive care showed modest increase during the last 6 months of life, accelerating in the last month, for all patient populations. For patients with COPD and heart failure, the PP of receiving home care remained stable during the last 6 months of life but increased steadily for patients with cancer.

CONCLUSION

We found limited differences in healthcare resource utilisation at the end of life for people with COPD, heart failure or cancer, indicating comparable illness trajectories.This supports the need to reconsider efforts in achieving equal access to palliative care interventions, which is still mainly offered to patients with cancer.

Long-term trends in critical care admissions in Wales

As national populations age, demands on critical care services are expected to increase. In many healthcare settings, longitudinal trends indicate rising numbers and proportions of patients admitted to ICU who are older; elsewhere, including some parts of the UK, a decrease has raised concerns with regard to rationing according to age. Our aim was to investigate admission trends in Wales, where critical care capacity has not risen in the last decade. We used the Secure Anonymised Information Linkage Databank to identify and characterise critical care admissions in patients aged ≥ 18 years from 1 January 2008 to 31 December 2017. We categorised 85,629 ICU admissions as youngest (18-64 years), older (65-79 years) and oldest (≥ 80 years). The oldest group accounted for 15% of admissions, the older age group 39% and the youngest group 46%. Relative to the national population, the incidence of admission rates per 10,000 population in the oldest group decreased significantly over the study period from 91.5/10,000 in 2008 to 77.5/10,000 (a relative decrease of 15%), and among the older group from 89.2/10,000 in 2008 to 75.3/10,000 in 2017 (a relative decrease of 16%). We observed significant decreases in admissions with high comorbidity (modified Charlson comorbidity index); increases in the proportion of older patients admitted who were considered 'fit' rather than frail (electronic frailty index); and decreases in admissions with a medical diagnosis. In contrast to other healthcare settings, capacity constraints and surgical imperatives appear to have contributed to a relative exclusion of older patients presenting with acute medical illness.

Long-term mortality of patients discharged from the hospital after successful critical care in the ICU in Korea: a retrospective observational study in a single tertiary care teaching hospital

Background

The long-term outcomes of patients discharged from the hospital after successful care in intensive care unit (ICU) are not briskly evaluated in Korea. The aim of this study was to assess long-term mortality of patients treated in the ICU and discharged alive from the hospital and to identify predictive factors of mortality.

Methods

In 3,679 adult patients discharged alive from the hospital after ICU care between 2006 and 2011, the 1-year mortality rate (primary outcome measure) was investigated. Various factors were entered into multivariate analysis to identify independent factors of 1-year mortality, including sex, age, severity of illness (APACHE II score), mechanical ventilation, malignancy, readmission, type of admission (emergency, elective surgery, and medical), and diagnostic category (trauma and non-trauma).

Results

The 1-year mortality rate was 13.4%. Risk factors that were associated with 1-year mortality included age (hazard ratio: 1.03 [95% CI, 1.02–1.04], P < 0.001), APACHE II score (1.03 [1.01–1.04], P < 0.001), mechanical ventilation (1.96 [1.60–2.41], P < 0.001), malignancy (2.31 [1.82–2.94], P < 0.001), readmission (1.65 [1.31–2.07], P < 0.001), emergency surgery (1.66 [1.18–2.34], P = 0.003), ICU admission due to medical causes (4.66 [3.68–5.91], P < 0.001), and non-traumatic diagnostic category (6.04 [1.50–24.38], P = 0.012).

Conclusions

The 1-year mortality rate was 13.4%. Old age, high APACHE II score, mechanical ventilation, malignancy, readmission, emergency surgery, ICU admission due to medical causes, and non-traumatic diagnostic category except metabolic/endocrinologic category were associated with 1-year mortality.

Influenza vaccination and 1-year risk of myocardial infarction, stroke, heart failure, pneumonia, and mortality among intensive care unit survivors aged 65 years or older: a nationwide population-based cohort study

PURPOSE

We examined whether influenza vaccination affects 1-year risk of myocardial infarction, stroke, heart failure, pneumonia, and death among intensive care unit (ICU) survivors aged ≥ 65 years.

METHODS

Danish Intensive Care Database data on all elderly ( ≥ 65 years) patients hospitalized in Danish ICUs in the period 2005-2015, and subsequently discharged, were linked with data from other medical registries, including data on uptake of the seasonal influenza vaccine. We computed these patients' 1-year risk of hospitalization for myocardial infarction, stroke, heart failure, or pneumonia, and their 1-year risk of all-cause mortality. Hazard ratios (HRs) with 95% confidence intervals (CIs) were computed using Cox proportional hazards regression, with adjustment and propensity score matching applied to handle confounding.

RESULTS

The study included 89,818 ICU survivors. The influenza vaccinated patients (n = 34,871, 39%) were older, had more chronic diseases, and used more prescription medications than the unvaccinated patients. Adjusted 1-year mortality was decreased among the vaccinated versus the unvaccinated patients (19.3% versus 18.8%; adjusted HR, 0.92; 95% CI 0.89-0.95). Influenza vaccination was also associated with a decreased risk of stroke (adjusted HR, 0.84; 95% CI 0.78-0.92), but only a small, non-significantly decreased risk of myocardial infarction (adjusted HR, 0.93; 95% CI 0.83-1.03). There was no association between vaccination and subsequent hospitalization for heart failure or pneumonia. Propensity score matched analyses confirmed these findings.

CONCLUSIONS

Compared with the unvaccinated ICU survivors, the influenza vaccinated ICU survivors had a lower 1-year risk of stroke and a lower 1-year risk of death, whereas no substantial association was observed for the risk of hospitalization for myocardial infarction, heart failure, or pneumonia. Our findings support influenza vaccination of individuals aged ≥ 65 years.

A latent class analysis of prolonged mechanical ventilation patients at a long-term acute care hospital: Subtype differences in clinical outcomes

RATIONALE

Patients on prolonged mechanical ventilation (PMV) at Long-Term Acute Care Hospital's (LTACHs) are clinically heterogeneous making it difficult to manage care and predict clinical outcomes.

OBJECTIVES

Identify and describe subgroups of patients on PMV at LTACHs and examine for group differences.

METHODS

Latent class analysis was completed on data obtained during medical record review at Midwestern LTACH.

MAIN RESULTS

A three-class solution was identified. Class 1 contained young, obese patients with low clinical and co-morbid burden; Class 2 contained the oldest patients with low clinical burden but multiple co-morbid conditions; Class 3 contained patients with multiple clinical and co-morbid burdens. There were no differences in LTACH length of stay [F(2,246) = 2.243, p = 0.108] or number of ventilator days [F(2,246) = 0.641, p = 0.528]. Class 3 patients were less likely to wean from mechanical ventilation [χ²(2, N = 249) = 25.48, p < 0.001] and more likely to die [χ²(2, N = 249) = 23.68, p < 0.001].

CONCLUSION

Patient subgroups can be described that predict clinical outcomes. Class 3 patients are at higher risk for poor clinical outcomes when compared to patients in Class 1 or Class 2.

Arguing for Adaptive Clinical Trials in Sepsis

Sepsis is life-threatening organ dysfunction due to dysregulated response to infection. Patients with sepsis exhibit wide heterogeneity stemming from genetic, molecular, and clinical factors as well as differences in pathogens, creating challenges for the development of effective treatments. Several gaps in knowledge also contribute: (i) biomarkers that identify patients likely to benefit from specific treatments are unknown; (ii) therapeutic dose and duration is often poorly understood; and (iii) short-term mortality, a common outcome measure, is frequently criticized for being insensitive. To date, the majority of sepsis trials use traditional design features, and have largely failed to identify new treatments with incremental benefit over standard of care. Traditional trials are also frequently conducted as part of a drug evaluation process that is segmented into several phases, each requiring separate trials, with a long time delay from inception through design and execution to incorporation of results into clinical practice. By contrast, adaptive clinical trial designs facilitate the evaluation of several candidate treatments simultaneously, learn from emergent discoveries during the course of the trial, and can be structured efficiently to lead to more timely conclusions compared to traditional trial designs. Adoption of new treatments in clinical practice can be accelerated if these trials are incorporated in electronic health records as part of a learning health system. In this review, we discuss challenges in the evaluation of treatments for sepsis, and explore potential benefits and weaknesses of recent advances in adaptive trial methodologies to address these challenges.

Precision medicine for all? Challenges and opportunities for a precision medicine approach to critical illness

All of medicine aspires to be precise, where a greater understanding of individual data will lead to personalized treatment and improved outcomes. Prompted by specific examples in oncology, the field of critical care may be tempted to envision that complex, acute syndromes could bend to a similar reductionist philosophy-where single mutations could identify and target our critically ill patients for treatment. However, precision medicine faces many challenges in critical care. These include confusion about terminology, uncertainty about how to divide patients into discrete groups, the challenges of multi-morbidity, scale, and the need for timely interventions. This review addresses these challenges and provides a translational roadmap spanning preclinical work to identify putative treatment targets, novel designs for clinical trials, and the integration of the electronic health record to implement precision critical care for all.

The Danish Intensive Care Database

AIM OF DATABASE

The aim of this database is to improve the quality of care in Danish intensive care units (ICUs) by monitoring key domains of intensive care and to compare these with predefined standards.

STUDY POPULATION

The Danish Intensive Care Database (DID) was established in 2007 and includes virtually all ICU admissions in Denmark since 2005. The DID obtains data from the Danish National Registry of Patients, with complete follow-up through the Danish Civil Registration System.

MAIN VARIABLES

For each ICU admission, the DID includes data on the date and time of ICU admission, type of admission, organ supportive treatments, date and time of discharge, status at discharge, and mortality up to 90 days after admission. Descriptive variables include age, sex, Charlson comorbidity index score, and, since 2010, the Simplified Acute Physiology Score (SAPS) II. The variables are recorded with 90%-100% completeness in the recent years, except for SAPS II score, which is 73%-76% complete. The DID currently includes five quality indicators. Process indicators include out-of-hour discharge and transfer to other ICUs for capacity reasons. Outcome indicators include ICU readmission within 48 hours and standardized mortality ratios for death within 30 days after admission using case-mix adjustment (initially using age, sex, and comorbidity level, and, since 2013, using SAPS II) for all patients and for patients with septic shock.

DESCRIPTIVE DATA

The DID currently includes 335,564 ICU admissions during 2005-2015 (average 31,958 ICU admissions per year).

CONCLUSION

The DID provides a valuable data source for quality monitoring and improvement, as well as for research.

Intensive care at the end of life in patients dying due to non-cancer chronic diseases versus cancer: a nationwide study in Denmark

Introduction

It is unknown to what extent use of palliative care and focus on proactive planning of end-of-life (EOL) care among cancer patients is also reflected by less use of intensive care. We aimed to examine the use of intensive care in the EOL in patients dying as a result of non-cancer diseases compared with patients dying due to cancer.

Methods

We conducted a nationwide follow-up study among 240,757 adults dying as a result of either non-cancer chronic disease or cancer in Denmark between 2005 and 2011. Using the Danish Intensive Care Database, we identified all admissions and treatments in intensive care units (ICU) during the patients’ last 6 months before death. We used prevalence ratios (aPRs) adjusted for age, sex, comorbidity, marital status and residential region to compare the 6-month prevalence of ICU admissions as well as treatment with invasive mechanical ventilation (MV), non-invasive ventilation (NIV), renal replacement therapy (RRT) and inotropes and/or vasopressors. In addition, length of ICU stay and death during ICU admission were compared among non-cancer and cancer patients dying between 2009 and 2011.

Results

Overall 12.3 % of non-cancer patients were admitted to an ICU within their last 6 months of life, compared with 8.7 % of cancer patients. The overall aPR for ICU admission was 2.11 [95 % confidence interval (CI) 1.98–2.24] for non-cancer patients compared with cancer patients and varied widely within the non-cancer patients (patients with dementia, aPR 0.19, 95 % CI 0.17–0.21; patients with chronic obstructive lung disease, aPR 3.19, 95 % CI 2.97–3.41). The overall aPRs for treatment among non-cancer patients compared with cancer patients were 1.40 (95 % CI 1.35–1.46) for MV, 1.62 (95 % CI 1.50–1.76) for NIV, 1.19 (95 % CI 1.07–1.31) for RRT and 1.05 (95 % CI 0.87–1.28) for inotropes and/or vasopressors. No difference in admission length was observed. Non-cancer patients had an increased risk of dying in an ICU (aPR 1.23, 95 % CI 0.99–1.54) compared with cancer patients.

Conclusions

Overall, patients dying as a result of non-cancer diseases were twice as likely to be admitted to ICUs at the EOL as patients dying due to cancer. Further studies are warranted to explore whether this difference in use of intensive care reflects an unmet need of palliative care, poor communication about the EOL or lack of prognostic tools for terminally ill non-cancer patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13054-015-1124-1) contains supplementary material, which is available to authorized users.

Pre-existing atrial fibrillation and risk of arterial thromboembolism and death in intensive care unit patients: a population-based cohort study

INTRODUCTION

Pre-existing atrial fibrillation (AF) may worsen prognosis in patients admitted to the intensive care unit (ICU).

METHODS

In a cohort study (2005-2011) including all patients with first-time ICU admissions in Denmark (n=57,110), we compared patients with and without pre-existing AF and estimated absolute risks and relative risks (RRs) of arterial thromboembolism and death within 30 days and 365 days following admission, using Kaplan-Meier methods and multivariate regression analyses. We analysed the prognostic impact of AF within strata of patient age, sex, coexisting cardiac diseases, and ICU therapies.

RESULTS

Among ICU patients, 5065 (9%) had pre-existing AF. Compared with patients without AF, those with AF were older (median age 75 vs. 62 years) and had more comorbidity. The risk of arterial thromboembolism was 2.8% in patients with AF and 2.0% in non-AF patients at 30 days, and 4.3% and 2.9%, respectively, at 365 days. Corresponding RRs were 1.41 crude and 1.14 (95% confidence interval [CI] 0.93-1.40) adjusted at 30 days, and 1.50 crude and 1.20 (95% CI 1.02-1.41) adjusted at 365 days. Thirty-day mortality was 27% in patients with pre-existing AF and 16% in non-AF patients (crude RR 1.67, adjusted RR 1.04, 95% CI 0.99-1.10). Corresponding mortality estimates at 365 days were 40.9% and 25.4%, respectively (crude RR 1.61, adjusted RR 1.03, 95% CI 1.00-1.07). In stratified analyses, pre-existing AF increased mortality in ICU patients aged <55 years (adjusted RR at 30 days 1.73, 95% CI 1.29-2.32; adjusted RR at 365 days 1.34, 95% CI 1.06-1.69) and in ICU patients treated with mechanical ventilation (adjusted RR at 30 days 1.12, 95% CI 1.05-1.20, adjusted RR at 365 days 1.09, 95% CI: 1.04-1.15). Analyses stratified by sex and coexisting cardiac diseases yielded adjusted RRs close to 1.

CONCLUSIONS

In ICU patients, pre-existing AF was associated with modestly increased risk of arterial thromboembolism when adjusted for the substantially higher age and comorbidity levels in patients with AF, whereas there was no overall association with mortality. In ICU patients aged <55 years and in those treated with mechanical ventilation, AF predicted increased mortality.

Geographical variation in use of intensive care: a nationwide study

PURPOSE

To examine whether there is geographical variation in the use of intensive care resources in Denmark concerning both intensive care unit (ICU) admission and use of specific interventions. Substantial variation in use of intensive care has been reported between countries and within the US, however, data on geographical variation in use within more homogenous tax-supported health care systems are sparse.

METHODS

We conducted a population-based cross-sectional study based on linkage of national medical registries including all Danish residents between 2008 and 2012 using population statistics from Statistics Denmark. Data on ICU admissions and interventions, including mechanical ventilation, noninvasive ventilation, acute renal replacement therapy, and treatment with inotropes/vasopressors, were obtained from the Danish Intensive Care Database. Data on patients' residence at the time of admission were obtained from the Danish National Registry of Patients.

RESULTS

The overall age- and gender standardized number of ICU patients per 1000 person-years for the 5-year period was 4.3 patients (95 % CI, 4.2; 4.3) ranging from 3.7 (95 % CI, 3.6; 3.7) to 5.1 patients per 1000 person-years (95 % CI, 5.0; 5.2) in the five regions of Denmark and from 2.8 (95 % CI, 2.8; 3.0) to 23.1 patients per 1000 person-years (95 % CI, 13.0; 33.1) in the 98 municipalities. The age-, gender-, and comorbidity standardized proportion of use of interventions among ICU patients also differed across regions and municipalities.

CONCLUSIONS

There was only minimal geographical variation in the use of intensive care admissions and interventions at the regional level in Denmark, but more pronounced variation at the municipality level.

Age, risk, and life expectancy in Norwegian intensive care: a registry-based population modelling study

Background

Knowledge about the expected life years gained from intensive care unit (ICU) admission could inform priority-setting decisions across groups of ICU patients and across medical specialties. The aim of this study was to estimate expected remaining lifetime for patients admitted to ICUs during 2008–2010 and to estimate the gain in life years from ICU admission.

Methods

This is a descriptive, population modelling study of 30,712 adult mixed ICU admissions from the Norwegian Intensive Care Registry. The expected remaining lifetime for each patient was estimated using a decision-analytical model. Transition probabilities were based on registered Simplified Acute Physiology Score (SAPS) II, and standard and adjusted Norwegian life-tables.

Results

The hospital mortality was 19.4% (n = 5,958 deaths). 24% of the patients were estimated to die within the first year after ICU admission in our model. Under an intermediate (base case), optimistic (O), and pessimistic (P) scenario with respect to long-term mortality, the average expected remaining lifetime was 19.4, 19.9, and 12.7 years. The majority of patients had a life expectancy of more than five years (84.8% in the base case, 89.4% in scenario O, and 55.6% in scenario P), and few had a life expectancy of less than one year (0.7%, 0.1%, and 12.7%). The incremental gain from ICU admission compared to counterfactual general ward care was estimated to be 0.04 (scenario P, age 85+) to 1.14 (scenario O, age < 45) extra life years per patient.

Conclusions

Our research demonstrated a novel way of using routinely collected registry data to estimate and evaluate the expected lifetime outcomes for ICU patients upon admission. The majority had high life expectancies. The youngest age groups seemed to benefit the most from ICU admission. The study raises the question whether availability and rationing of ICU services are too strict in Norway.

The impact of chronic obstructive pulmonary disease on intensive care unit admission and 30-day mortality in patients undergoing colorectal cancer surgery: a Danish population-based cohort study

Background and purpose

Chronic obstructive pulmonary disease (COPD) may increase the risk of postoperative complications and thus mortality after colorectal cancer (CRC) surgery, but the evidence is sparse.

Methods

We conducted this nationwide population-based cohort study in Denmark, including all patients undergoing CRC surgery in the period 2005–2011, identified through medical databases. We categorised the patients according to the history of COPD.

We assessed the rate of complications within 30 days. We computed 30-day mortality among patients with/without COPD using the Kaplan-Meier method. We used Cox regression to compute HRs for death, controlling for age, gender, type of admission, cancer stage, hospital volume, alcohol-related diseases, obesity and Charlson comorbidity score.

Results

We identified 18 302 CRC surgery patients. Of these, 7.9% had a prior diagnosis of COPD. Among patients with COPD, 16.1% were admitted postoperatively to the intensive care unit, 1.9% were treated with mechanical ventilation, and 3.6% were treated with non-invasive ventilation. In patients without COPD, the corresponding proportions were 9.7%, 1.1% and 1.1%. The reoperation rate was 10.6% among patients with COPD and 8% among patients with cancer without COPD. 30-day mortality was 13% (95% CI 11.4% to 14.9%) among patients with COPD and 5.3% (95% CI 5.0% to 5.7%) among patients without COPD, corresponding to an adjusted HR of 1.7 (95% CI 1.5 to 2.0).

Conclusions

COPD is a strong predictor for intensive care unit admission and mortality after CRC surgery.

A rehabilitation intervention to promote physical recovery following intensive care: a detailed description of construct development, rationale and content together with proposed taxonomy to capture processes in a randomised controlled trial

BACKGROUND

Increasing numbers of patients are surviving critical illness, but survival may be associated with a constellation of physical and psychological sequelae that can cause ongoing disability and reduced health-related quality of life. Limited evidence currently exists to guide the optimum structure, timing, and content of rehabilitation programmes. There is a need to both develop and evaluate interventions to support and expedite recovery during the post-ICU discharge period. This paper describes the construct development for a complex rehabilitation intervention intended to promote physical recovery following critical illness. The intervention is currently being evaluated in a randomised trial (ISRCTN09412438; funder Chief Scientists Office, Scotland).

METHODS

The intervention was developed using the Medical Research Council (MRC) framework for developing complex healthcare interventions. We ensured representation from a wide variety of stakeholders including content experts from multiple specialties, methodologists, and patient representation. The intervention construct was initially based on literature review, local observational and audit work, qualitative studies with ICU survivors, and brainstorming activities. Iterative refinement was aided by the publication of a National Institute for Health and Care Excellence guideline (No. 83), publicly available patient stories (Healthtalkonline), a stakeholder event in collaboration with the James Lind Alliance, and local piloting. Modelling and further work involved a feasibility trial and development of a novel generic rehabilitation assistant (GRA) role. Several rounds of external peer review during successive funding applications also contributed to development.

RESULTS

The final construct for the complex intervention involved a dedicated GRA trained to pre-defined competencies across multiple rehabilitation domains (physiotherapy, dietetics, occupational therapy, and speech/language therapy), with specific training in post-critical illness issues. The intervention was from ICU discharge to 3 months post-discharge, including inpatient and post-hospital discharge elements. Clear strategies to provide information to patients/families were included. A detailed taxonomy was developed to define and describe the processes undertaken, and capture them during the trial. The detailed process measure description, together with a range of patient, health service, and economic outcomes were successfully mapped on to the modified CONSORT recommendations for reporting non-pharmacologic trial interventions.

CONCLUSIONS

The MRC complex intervention framework was an effective guide to developing a novel post-ICU rehabilitation intervention. Combining a clearly defined new healthcare role with a detailed taxonomy of process and activity enabled the intervention to be clearly described for the purpose of trial delivery and reporting. These data will be useful when interpreting the results of the randomised trial, will increase internal and external trial validity, and help others implement the intervention if the intervention proves clinically and cost effective.

The PIRO (predisposition, insult, response, organ dysfunction) model: toward a staging system for acute illness

Multimodal therapy for diseases like cancer has only become practicable following the development of staging systems like the TNM (tumor, nodes, metastases) system. Staging enables the identification of subgroups of patients with a disease who not only have a differing prognosis, but who are also more likely to benefit from a specific therapeutic modality. Critically ill patients represent a highly heterogeneous population for whom multiple therapeutic options are potentially available, each carrying not only the potential for differential benefit, but also the potential for differential harm. The PIRO system (predisposition, insult, response, organ dysfunction) is a template proposal for a staging system for acute illness that incorporates assessment of pre-morbid baseline susceptibility (predisposition), the specific disorder responsible for acute illness (insult), the response of the host to that insult, and the resulting degree of organ dysfunction. However the creation of a valid, robust, and clinically useful system presents significant challenges arising from the complexity of the disease state, the lack of a clear phenotype, the confounding influence of the effects of therapy and of cultural and socio-economic factors, and the relatively low profile of acute illness with clinicians and the general public. This review summarizes the rationale for such a model of illness stratification and the results of preliminary cohort studies testing the concept. It further proposes two strategies for building a staging system, recognizing that this will be a demanding undertaking that will require decades of work.

Preadmission metformin use and mortality among intensive care patients with diabetes: a cohort study

Introduction

Metformin has anti-inflammatory and anti-thrombotic effects that may improve the outcome of critical illness, but clinical data are limited. We examined the impact of preadmission metformin use on mortality among intensive care unit (ICU) patients with type 2 diabetes.

Methods

We conducted this population-based cohort study among all persons admitted to the 17 ICUs in Northern Denmark (population approximately 1.8 million). We focused on all patients with type 2 diabetes who were admitted to the ICUs between January 2005 and December 2011. Through individual-level linkage of population-based medical databases, type 2 diabetes was identified using a previously validated algorithm including hospital diagnoses, filled prescriptions for anti-diabetic drugs, and elevated HbA1c levels. Metformin use was identified by filled prescriptions within 90 days before admission. Covariates included surgery, preadmission morbidity, diabetes duration, and concurrent drug use. We computed 30-day mortality and hazard ratios (HRs) of death using Cox regression adjusted for covariates, both overall and after propensity score matching.

Results

We included 7,404 adult type 2 diabetes patients, representing 14.0% of 52,964 adult patients admitted to the ICUs. Among type 2 diabetes patients, 1,073 (14.5%) filled a prescription for metformin as monotherapy within 90 days before admission and 1,335 (18.0%) received metformin in combination with other anti-diabetic drugs. Thirty-day mortality was 17.6% among metformin monotherapy users, 17.9% among metformin combination therapy users, and 25.0% among metformin non-users. The adjusted HRs were 0.80 (95% confidence interval (CI): 0.69, 0.94) for metformin monotherapy users and 0.83 (95% CI: 0.71, 0.95) for metformin combination therapy users, compared to non-users. Propensity-score-matched analyses yielded the same results. The association was evident across most subgroups of medical and surgical ICU patients, but most pronounced in elderly patients and in patients with well-controlled diabetes. Former metformin use was not associated with decreased mortality.

Conclusions

Preadmission metformin use was associated with reduced 30-day mortality among medical and surgical intensive care patients with type 2 diabetes.

Hospitalization rate and 30-day mortality among patients with status asthmaticus in Denmark: a 16-year nationwide population-based cohort study

Objective

Current data on hospitalization and prognosis of acute asthma and status asthmaticus are inconclusive. We aim to analyze the rate of first-time hospitalizations for status asthmaticus among patients of all ages, the proportion admitted to intensive care units (ICU), and the 30-day mortality over a 16-year period.

Methods

In this population-based cohort study, we used medical registries to identify all first-time status asthmaticus hospitalizations in Denmark from 1996 through 2011. Data on comorbidities were also obtained. We computed yearly hospitalization rates overall and by gender and age groups, and estimated the proportion requiring ICU admission. We estimated 30-day age- and gender-standardized mortality. We examined potential misclassification from acute exacerbation of chronic obstructive pulmonary disease (COPD) by excluding patients with preexisting or concurrent COPD.

Results

Of the 5,001 patients identified with a first-time status asthmaticus hospitalization, 50.5% were male, 40.3% were <15 years old, and 12.4% had comorbidity. The hospitalization rate increased from 48.0 per 1,000,000 person-years (PY) (95% confidence interval [CI]: 45.1–51.1 PY) during 1996–1999 to 70.1 per 1,000,000 PY (95% CI: 66.7–73.7 PY) during 2008–2011. This may be explained by an increased hospitalization rate of children. The standardized 30-day mortality risk declined from 3.3% (95% CI: 2.5%–4.1%) in 1996–1999 to 1.5% (95% CI: 0.9%–2.1%) in 2008–2011. During 2005–2011, 10.1% of status asthmaticus patients were admitted to the ICU. Hospitalization rates and mortality risk decreased by excluding 939 patients also registered with COPD, but overall temporal changes did not change.

Conclusion

From 1996 to 2011, status asthmaticus hospitalization rate increased but remained below 100 hospitalizations per 1,000,000 PY. Thirty-day mortality risk was halved to less than 2%.

Five-year risk of end-stage renal disease among intensive care patients surviving dialysis-requiring acute kidney injury: a nationwide cohort study

Introduction

Dialysis-requiring acute kidney injury (D-AKI) is common among intensive care unit (ICU) patients. However, follow-up data on the risk of end-stage renal disease (ESRD) among these patients remain sparse. We assessed the short-term and long-term risk of ESRD after D-AKI, compared it with the risk in other ICU patients, and examined the risk within subgroups of ICU patients.

Methods

We used population-based medical registries to identify all adult patients admitted to an ICU in Denmark from 2005 through 2010, who survived for 90 days after ICU admission. D-AKI was defined as needing acute dialysis at or after ICU admission. Subsequent ESRD was defined as a need for chronic dialysis for more than 90 days or a kidney transplant. We computed the cumulative ESRD risk for patients with D-AKI and for other ICU patients, taking into account death as a competing risk, and computed hazard ratios (HRs) using a Cox model adjusted for potential confounders.

Results

We identified 107,937 patients who survived for 90 days after ICU admission. Of these, 3,062 (2.8%) had an episode of D-AKI following ICU admission. The subsequent risk of ESRD up to 180 days after ICU admission was 8.5% for patients with D-AKI, compared with 0.1% for other ICU patients. This corresponds to an adjusted HR of 105.6 (95% confidence interval (CI): 78.1 to 142.9). Among patients who survived 180 days after ICU admission without developing ESRD (n = 103,996), the 181-day to 5-year ESRD risk was 3.8% for patients with D-AKI, compared with 0.3% for other ICU patients, corresponding to an adjusted HR of 6.2 (95% CI: 4.7 to 8.1). During the latter period, the impact of AKI was most pronounced in the youngest patients, aged 15 to 49 years (adjusted HR = 12.8, 95% CI: 6.5 to 25.4) and among patients without preexisting chronic kidney disease (adjusted HR = 11.9, 95% CI: 8.5 to 16.8).

Conclusion

D-AKI is an important risk factor for ESRD for up to five years after ICU admission.

Validity of the coding for intensive care admission, mechanical ventilation, and acute dialysis in the Danish National Patient Registry: a short report

BACKGROUND

Large health care databases provide a cost-effective data source for observational research in the intensive care unit (ICU) if the coding is valid. The aim of this study was to investigate the accuracy of the recorded coding of ICU admission, mechanical ventilation, and acute dialysis in the population-based Danish National Patient Registry (DNPR).

METHODS

We conducted the study in the North Denmark Region, including seven ICUs. From the DNPR we selected a total of 150 patients with an ICU admission by the following criteria: (1) 50 patients randomly selected among all patients registered with an ICU admission code, (2) 50 patients with an ICU admission code and a concomitant code for mechanical ventilation, and (3) 50 patients with an ICU admission code and a concomitant code for acute dialysis. Using the medical records as gold standard we estimated the positive predictive value (PPV) for each of the three procedure codes.

RESULTS

We located 147 (98%) of the 150 medical records. Of these 147 patients, 141 (95.9%; 95% confidence interval [CI]: 91.8-98.3) had a confirmed ICU admission according to their medical records. Among patients, who were selected only on the coding for ICU admission, the PPV for ICU admission was 87.2% (95% CI: 75.6-94.5). For the mechanical ventilation code, the PPV was 100% (95% CI: 95.1-100). Forty-nine of 50 patients with the coding for acute dialysis received this treatment, corresponding to a PPV of 98.0% (95% CI: 91.0-99.8).

CONCLUSION

We found a high PPV for the coding of ICU admission and even higher PPVs for mechanical ventilation, and acute dialysis in the DNPR. The DNPR is a valuable data source for observational studies of ICU patients.

One-year mortality among Danish intensive care patients with acute kidney injury: a cohort study

INTRODUCTION

There are few studies on long-term mortality among intensive care unit (ICU) patients with acute kidney injury (AKI). We assessed the prevalence of AKI at ICU admission, its impact on mortality during one year of follow-up, and whether the influence of AKI varied in subgroups of ICU patients.

METHODS

We identified all adults admitted to any ICU in Northern Denmark (approximately 1.15 million inhabitants) from 2005 through 2010 using population-based medical registries. AKI was defined at ICU admission based on the risk, injury, failure, loss of kidney function, and end-stage kidney disease (RIFLE) classification, using plasma creatinine changes. We included four severity levels: AKI-risk, AKI-injury, AKI-failure, and without AKI. We estimated cumulative mortality by the Kaplan-Meier method and hazard ratios (HRs) using a Cox model adjusted for potential confounders. We computed estimates for all ICU patients and for subgroups with different comorbidity levels, chronic kidney disease status, surgical status, primary hospital diagnosis, and treatment with mechanical ventilation or with inotropes/vasopressors.

RESULTS

We identified 30,762 ICU patients, of which 4,793 (15.6%) had AKI at ICU admission. Thirty-day mortality was 35.5% for the AKI-risk group, 44.2% for the AKI-injury group, and 41.0% for the AKI-failure group, compared with 12.8% for patients without AKI. The corresponding adjusted HRs were 1.96 (95% confidence interval (CI) 1.80-2.13), 2.60 (95% CI 2.38 to 2.85) and 2.41 (95% CI 2.21 to 2.64), compared to patients without AKI. Among patients surviving 30 days (n = 25,539), 31- to 365 day mortality was 20.5% for the AKI-risk group, 23.8% for the AKI-injury group, and 23.2% for the AKI-failure group, compared with 10.7% for patients without AKI, corresponding to adjusted HRs of 1.33 (95% CI 1.17 to 1.51), 1.60 (95% CI 1.37 to1.87), and 1.64 (95% CI 1.42 to 1.90), respectively. The association between AKI and 30-day mortality was evident in subgroups of the ICU population, with associations persisting in most subgroups during the 31- to 365-day follow-up period, although to a lesser extent than for the 30-day period.

CONCLUSIONS

AKI at ICU admission is an important prognostic factor for mortality throughout the subsequent year.